As your brain ages, it naturally shrinks in size. Cognitive decline and dementia are caused by shrinkage of the brain and are accelerated by alcohol, smoking…and body fat. Research from the University of Cambridge calculates that overweight 50-year-olds have the brain of a 60-year-old.

One of the researchers, Dr Lenore Launer, explains that “the more we understand about body fat the clearer it becomes that belly fat is its own disease-generating organism.”

The researchers divided subjects into two groups: overweight (BMI 25+) and lean (BMI <25).

To put that into context the line that defined overweight and lean was calculated in relation to your height: 150cm (56kg), 160cm (64kg), 170cm (72kg), 180cm (81kg), 190cm (90kg) and 200cm (100kg).

Subjects underwent an MRI to measure the volume of their brain. What they found was a dramatic reduction in the amount of white matter in overweight subjects. The white matter connects areas of the brain and allows information to be communicated between regions.

The researchers only observed this different from middle age onwards, suggesting that your brain may be particularly vulnerable during this period of ageing.

When the data was compared to age, an overweight person at 50 had a comparable white matter volume to a lean person at 60

The researchers expected to find differences in cognitive function but when they tested for IQ no difference was recorded. Where the overweight falls down is the executive function — planning, organising, decision-making.

What is encouraging is that research into fat loss indicates that it reverses the negative effect on the brain. A study of obese women about to undergo bariatric surgery found their level of executive function improved post weight loss.

The exact mechanism of this reduction in volume is yet to be unequivocally proven. Although it’s most likely to be inflammation that leads to structural damage to the brain.

Like any inflammation removing the trigger causing the inflammation results in a swift reduction.

In this case, the trigger is body fat. To reverse the effect of ageing on the brain all you need to do is lose it.

The process explained above is something I call ‘executive decline’. This is a pattern that I have seen over the past 13 years training over 1000 executive clients. What is executive decline and what to do about it is explained here in this PDF download.